ML20086J004

Telecopy AO 75-24:on 750401,stem on Hpsw/Rhr HX Discharge Valve MO-2-10-89D Failed.Caused by High Valve Vibration Due to Throttling Mode of Valve Causing Disc Lock Nut Tack Welds to Fracture & Nut to Back Off

ML20086J004
Person / Time
Site:	Peach Bottom
Issue date:	04/01/1975
From:	Ullrich W PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20086H997	List: ML20086H995 ML20086J004
References
AO-75-24, NUDOCS 8401230038
Download: ML20086J004 (1)

Text

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g(D) PHILADEI.FHIA ELECDt1C COMPANf hb /ili' Feach IL3ttom Atomic Pcwer Station Delta Pennsylvania I , gg hd 17314 Mr. Jame s F. O'Reilly. Director April 2, 1975 Office of Inspection and Enforcement Reston 1 United States Nuclear Regulatory Commisalon _ 631 Park Avenne King of Prussia, Pennsylvania 19406 +

Subject:

Aboormal Occurrene a 24-Hour Notification Confirming V. T. U11 rich's phone convers.-tion with Mr. Eldon Brunner, Region 1 United States Buclear Regulatory Commission on April 1,1975.

Reference:

License Number DFR-44' Technical Specification Reference 3.5.B 1 Report No.: 50-277-75-24 Report Date: April 2. 1975 Occurrence Date: April 1,1975 Facility: Peach Bottom Atomic Power Station R.D. 1, Delta, Pennsylvania 17314 ^ Identification of Occurrence: / ' Failure of the stem en EPSU/RRR beat exchanger discharga valva Oc-2-10-89D). Conditions Prior to Occurrence: , Reactor at approximately full power.

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Description of Occurrence: ".}/ =(. Y During routine Jf d ", the HPSV RER heat surveillance testing of the RER system, it was noted that with g $O p(F .S flow was stil.1 appreciable.exchan=:er discharge valve indicating full closed, the HPSV

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                                                                                                                           .c-n-g Designation of Apparent Causa of Occurrence:                                                                       3 .*W
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Righ valve vibration, due to the throttling mode of the valve, caused the disc i ' l',[ , '( d lock nut ,x P tack welds to fracture allowing the nut to back off. The loosening of ' j(,- the stem indisc the valve the increased stem vibration, and resulted in a fatigue failure of yobe bushing area. 14 Analysis of the Occurrence: f'fQ'.,[ [m. .. E W-{M The safety capability significance of the RER/EPSVof this was occurrence is considered minimal, since no cooling h lost. Corrective Action: e.n e.

                                                                                                                              .M Until  repairs can be made, EPSV will not be available to the 'D' exchanger.                                                                   RER ha at Bowever, all four LPCI loops are availabla, es arer                                       1.h                  [j PECompany Engineering is actively pursuing other mechanisms to reduce vibrationsall four HPSV punes.    .
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       \            in this Failure  Data:area which are believed to be the cause of this and similar f ailures.

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No previous stem failure has been experienced, but vibration inda. aced problems have >N. .- been_ reported as Abnormal Occurrences on these reports: AD-50-277-74-53, 7""' ff g' AD-50-2 78-74-28. AO--50-2 78-74-35 AO-50-2 78-74-36. and AD-50-2 78- 75-5. L'. 2, V Very truly yours. p  ? - p'.. .;:wy.: L N/NW& V. T. U Alrich. Superintendent

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   .       PDR ADOCK 05000277                                                                                             - - - -

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